Understanding the UAC

I am trying to install some software, which tells me to turn off User Account Controls before proceeding. In the relevant part of Control Panel there is an option to Turn User Account Controls on or off. When I click on that, the regular UAC message comes up and it then goes to a screen with a single box to check to turn UAC on. That implies that if you leave it unchecked the controls will not be on. If I click OK (or Cancel) to leave that screen, then try to return to the screen, the standard UAC message comes up again, which implies that the controls are still on.

Is there anywhere that tells you whether the controls are on or off? I am at Administrator level, but I was wondering if there was some other control that prevents me from changing the UAC.

I tried installing the software anyway, but it just stopped after a couple of seconds without any message. Before following that side of things up I wanted to see if I had misunderstood the way the UAC works. I hope someone can help. It does seem rather a basic question.

I spent a lot of time looking at how the UAC was meant to work, but couldn't find any way round my problem. Though I was convinced it was Vista, not the software that I was trying to install, that was the problem, I thought it might be useful to contact the suppliers to see if they had an answer. It seemed a good idea to have the screens in question in front of me when I phoned them, so I brought up the UAC updating screen and started the software installation. This time, at about the 10th attempt, it went through smoothly, and the installation completed successfully.

The only conclusion I can draw, is that while you are updating the UAC, its controls are not actually in place.